Drilling apparatus with a decoupled force frame and metrology frame for enhanced positioning

ABSTRACT

A printed circuit board (PCB) drilling apparatus that greatly increases the speed, accuracy and depth of the drilling process as well as increasing the life of the drill bits by decoupling the reactionary forces encountered in the positioning and drilling functions of the apparatus in the x, y and z axes from the components that accomplish the positioning, measuring and drilling of the stacked printed circuit boards. The part of the apparatus that moves and drills as well as the feedback position sensors are mounted to a set of vibration isolation pads that absorb the vibrations that would disturb the feedback sensors. Additionally, the force frame of the apparatus that experiences the reactionary force movements are decoupled from the metrology frame of the apparatus that house the feedback sensors, also increasing the throughput and accuracy.

The present invention involves a novel design for a printed circuitboard (PCB) substrate drilling machine that greatly increases the speed,accuracy and depth of the drilling process as well as increasing thelife of the drill bits.

BACKGROUND OF THE INVENTION

There is a huge industry developed around the demand to drill multiple,spaced holes (through or non-through) in substrates such as electronicwafers, thin film electronics, organic packaging substrates, glass,silicon wafers, sapphires or the like. These holes or patterneddrillings may be used for electrical connections, filtration, cytology,bioassays, chemotaxis, or particle monitoring and have diameters thatcommonly lie in the micron range. Not only must the holes be identicalto each other in diameter but also must be placed at precise locationsand with the right geometry with respect to the substrate or adjacentholes.

Generally, such drilling machines see movement in all three axessimultaneously. The substrate is positionally moved in the horizontal xaxis beneath a drill that plunges in the z vertical axis after the drillhas been positionally moved in the Y horizontal axis atop the substrateby a gantry unit. Drilling is initiated once the substrate is in theproper position as indicated by a set of metrology positioning sensorson the machine and at least one pressure foot has secured the PCBsubstrate on the x axis table to the z axis drill unit. This positioningprior to drilling occurs extremely rapidly by computer control, cyclingup to thousands of times per minute. Pursuant to Newton's third law ofmotion, each of these three positioning or drilling movements creates areactionary force in the structure of the PCB substrate drillingmachine. Since it is this machine that metrology positioning sensors arecoupled to, the settling time or lag for the PCB substrate to bepositioned within the acceptable ranges of the feedback sensors isslowed by the effects of the reactionary forces, thus slowing thepositioning process and adding slight inaccuracies in the positioningand eventual placement of the holes in the PCB.

Prior art PCB substrate drilling systems rely on the use of a massive,heavy machine base to minimize these reactionary forces coupled withlight moving masses, however, these reactionary forces still inherentlyreside in the machine and serve to limit the speed and accuracy at whichthe machine can function. When drilling micro holes or vias of 100microns or less in diameter at a rates higher than 15 cycles per second,the positioning accelerations increase to meet the point to pointpositioning commands and the disturbances that are injected into theheavy machine base cause the settling time at the end of eachpositioning to become longer thus cancelling out any move time reductiongained by the improved acceleration of the lighter moving masses.Additionally, the sensors operate with moderately large settling windows(in the 0.1 micron range) in the x and y axes. These prior art solutionsthat increase the mass of the machine base (reaction mass) and make themoving masses lighter do not completely address the root cause of theproblem—that the unitary base design supports both the metrology systemand the drilling system.

Henceforth, a PCB substrate drilling machine with improved accuracy andspeed, faster and deeper drilling depth (increased PCB substrate stackheights), longer drill bit life, less drill bit breakage and a highermachine throughput would fulfill a long felt need in the substratedrilling and surface patterning industry. This new invention utilizesand combines known and new technologies in a unique and novelconfiguration to overcome the aforementioned problems and accomplishthis.

SUMMARY OF THE INVENTION

The present invention, which will be described subsequently in greaterdetail, relates to a PCB substrate drilling apparatus adapted to provideboth speed and accuracy for the user resulting in a higher throughput.More particularly, to a PCB substrate drilling apparatus that decouplesany reactionary forces from the x axis and y axis positioning away fromthe measurement and positioning components, and balances the z axisdrilling forces of the apparatus so as to enable a much more efficientoperation capable of drilling a larger stack of PCB substrates. It hasmany of the advantages mentioned heretofore and many novel featureswhich are not anticipated, rendered obvious, suggested, or even impliedby any of the prior art, either alone or in any combination thereof.

In accordance with the invention, an object of the present invention isto provide an improved PCB substrate drilling apparatus having adecoupled force frame and metrology frame to enable enhanced positioningand drilling.

It is another object of this invention to provide an improved PCBsubstrate drilling apparatus capable of surpassing the current number ofstacked PCB substrates that can be drilled at the same time and remainwithin operational tolerances.

It is a further object of this invention to provide a PCB substratedrilling apparatus that maximizes the life of the drill bits andincreases the precision of the location of the drilled holes.

It is still a further object of this invention to provide for a PCBsubstrate drilling apparatus that minimizes or eliminates allreactionary force effects from the positioning and drilling functionsthat are created by the apparatuses' moving components.

The subject matter of the present invention is particularly pointed outand distinctly claimed in the concluding portion of this specification.However, both the organization and method of operation, together withfurther advantages and objects thereof, may best be understood byreference to the following description taken in connection withaccompanying drawings wherein like reference characters refer to likeelements. Other objects, features and aspects of the present inventionare discussed in greater detail below.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofthat follows may be better understood and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject matter of the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a prior art PCB substrate drilling apparatusillustrating the operational and reactionary forces;

FIG. 2 is a front view of the PCB substrate drilling apparatus of thepresent invention illustrating the separation of the operational andreactionary forces;

FIG. 3 is a perspective view of the PCB substrate drilling apparatus;

FIG. 4 is a front view of the PCB substrate drilling apparatus;

FIG. 5 is a side view of the PCB substrate drilling apparatus;

FIG. 6 is a back view of the PCB substrate drilling apparatus;

FIG. 7 is a top view of the PCB substrate drilling apparatus;

FIG. 8 is a perspective view of the z axis drill unit;

FIG. 9 is a front view of the z axis drill unit; and

FIG. 10 is a side view of the z axis drill unit.

DETAILED DESCRIPTION

All discussion of the geometry involved in describing the presentinvention is made with reference to a three dimensional CartesianCoordinate System where the z axis is vertical and pointing up (positiveup), so that the x and y axes lie on a horizontal plane where the x axisis shown as positive pointing “out of the page” towards the viewer, andthey axis is shown as positive on the right side of the z axis.

Generally, PCB substrate drilling machines perform four functions:staging (positioning) of the PCB substrates to be drilled in the correctx axis location on their moveable table, locating the drilling unit inthe correct y axis location above the PCB substrate stacks on themoveable table; feedback sensor measurement and verification of thelocation of the moveable table in relation to the drilling unit; andplunging the drill bit in the z axis into the stacked PCB substrates. Inthe prior art devices, the measurement function (metrology) isaccomplished by position feedback sensors located on the same frame ofthe device that accomplishes the positioning and drilling. This framehas a huge mass base, generally a planar granite or cement slab, intowhich the reactionary forces of the positioning and drilling functionsis passed. Its large mass minimizes any reactionary force movement thatis experienced by this slab, thereby passing very little of thesereactionary forces onto the actual positioning, measuring and drillingcomponents. This has several benefits. First, it minimizes the settlingtime of the positioning feedback sensors (the time after the positioningof the moveable table is completed until the sensor sees no furthermovement or backlash and can initiate the signal to begin the drilling.)Second, it prevents any additional, unwanted movement of the x axismovable table, the y axis moveable trolly and the z axis drilling unitwhich will reduce the accuracy of the PCB stack location. Third, andlastly, it helps ensure that the drill bits enter the PCB board stacksat precisely 90 degrees and thus do not drift too far off of theirdesired mark on the bottom PCB substrate.

Albeit, these reactionary force movements are minimized with thisfix—but not neglible. While these unwanted movements may have beenacceptably minimized with large scale drilling, this is not the casewith PCB substrate holes which are in the 10-100 micron range. In thishuge mass base or frame, the reaction forces when absorbed, turn intolow accelerations and one must hope the position feedback sensors arenot disturbed at a frequency that will cause a loss in system accuracy.The primary reason why this heavy base design is so prominent is becauseof the prominent the use of ball screw drives. However, with the adventof cost competitive linear motors it is now possible to make a machinetool architecture that utilizes the decoupled force frame/metrologyframe architecture.

Total elimination of these reactionary force movements would drasticallyimprove the operation of such devices. The present apparatus deals withthe removal of these reactionary force movements in all axes in two waysthat result in a new apparatus architecture. First, the presentapparatus separates or decouples the apparatus into two frames—a forceframe to accept the x axis and y axis reactionary forces, and ametrology frame that houses the feedback sensors used to position thePCB substrate stacks for drilling. The importance of keeping thereactionary force movements from disturbing position feedback iscritical, for the feedback sensor unit is only as good as theenvironment it is in. If the frame that the feedback sensor encoders arepositioned on has extensive vibrations, it will lose its ability toproperly measure the x, y and z axis positions of the apparatus'components as indicated by the encoding strips. (Although, generallyposition feedback is done by a feedback sensor unit that has an encodingstrip and an optical encoder that senses the encoding stip, it is knowthat other position feedback sensor units may be utilized with thispresent invention.) Second, it utilizes a balanced reactionary forcedrill unit that passes no reactionary forces from the downward andupward stroke of the drill spindle onto the metrology frame. Thecombination of these fixes eliminates all of the movement fromreactionary forces in all three axes resulting in shorter cycle times(due to quicker positioning sensor settling times), less drill bit wearand breakage (due to precise 90 degree drilling geometry), highermultiple PCB substrate stacks (due to less drill bit wander.)

Simply stated, the output of the present invention far exceeds that ofthe prior art and provides a much more accurately positioned hole on thePCB substrates. FIG. 1 illustrates the operational concept of the priorart and FIG. 2 illustrates the operational concept of the presentinvention's decoupled force frame/metrology frame design that results inthe enhanced machine stability.

It is to be noted that for the purposes of clarity the position feedbacksensors, the drilling and drive computer, the pressure feet and thedrill drive equipment are not illustrated as they are well known in theindustry and their inclusion in the figures would just serve to hamperthe clarity for the overall representation and understanding of thepresent invention. In the preferred embodiments, a zero impact pressurefoot would be utilized as disclosed in EP 0266397 A4, EP 0461733 B1 andEP 0461733 A2.

Looking at FIGS. 3-7 the general arrangement of all components of thePCB substrate drilling apparatus (the apparatus) 2 can best be seen. Areactionary force frame base mass 4 made of a dense material such asgranite, steel or concrete rests directly on the ground and serves tosupport the remainder of the apparatus's components. It generally weighsin the several ton range at a minimum. Actual weight varies with thesize of the apparatus it is coupled to. It is separated from themetrology frame support base 20 by a set of vibration isolationdampeners 8. These dampeners serve two functions. They prevent anyreactionary force motion or other vibrations from the base mass forceframe 4 from being transmitted to the metrology frame support base 20and table assembly 6, and they absorb any vibrations in the metrologyframe support base 20 that would disturb the feedback sensors. Thesevibration isolation dampeners 8 are of an elastomeric polymer, althougha metal spring or other compressible isolator that is well known in theindustry could be substituted. The vibration isolation dampeners 8 maybe mounted top and bottom on a set of plates 10 that are in turn affixedto the base mass force frame 4 and the metrology frame support base 20.Although depicted in sets of two and being located at the four cornersof the assembly 2, the actual placement and number of isolationdampeners may vary depending upon the size and configuration of theassembly. Although not shown in the figures, in an alternate embodimentthe isolation dampers are placed at the horizontal center of gravityplane of the metrology frame support base. The design illustrated inFIG. 3 would be modified such that the uppermost (top) plate of the pairof metal plates 10 would fit up into a stopped orifice in the metrologyframe support base such that its vertical position was verticallyaligned with the horizontal center of gravity plane for the metrologyframe support base. The top of this stopped orifice would serve as theupper contact point between the metrology frame support base 20 and theisolation damper 8. This type of modification would be well known it thefield of art. This aids to further eliminate any parasitic reactionaryforce disturbances.

The x axis moving table assembly 6 has an x axis moving table 12 coupledto the traveling arm 14 of the x axis linear drive unit. The x axislinear drive unit drives the traveling arm 14 along a stationary track16 based on a signal generated by the master control computer. On thismoving table 12 are located the encoding strips that enable the opticalencoders mounted on the metrology frame support base 20 to determine thetable's position and relay it to the computing means for generation of xaxis drive signals to the x axis linear drive unit to move the travelingarm 14, as well as the stacks of PCB substrate for drilling, which aremounted on the traveling table 12. The x axis traveling arm 14 iscoupled to the stationary drive track 16 of the x axis linear drive unitfor linear motion in the x axis by a low friction bearing means.Additional low friction bearings 18 act as a support between the bottomface of the x axis moving table 12 and the top face of the metrologyframe support base 20. The stationary drive track 16 is not coupled orconnected to the metrology frame support base 20, rather the stationarydrive track 16 of the x axis linear drive unit is directly coupled tothe base mass force frame 4 by the x axis reactionary force movementtransfer means 22. This is a stanchion made of a pair of rigid armsconnected by a beam 23 made of a steel, a metal, a polymer or compositeconstruction thereof, that the x axis stationary drive track 16 isaffixed to. It is an extension of the base mass force frame 4. (Althoughit is known that the x axis reactionary force movement transfer means 22may have a different physical configuration, it will remain a connectionbetween the x axis stationary drive track 16 and the base mass forceframe 4 and must isolate the x axis traveling arm 14 from the metrologyframe support base 20. Since the base mass force frame 4 is directlycoupled to the ground, connecting the x axis reactionary force movementtransfer means 22 directly to the ground rather than to the base massforce frame is deemed the equivalent to connecting the x axisreactionary force movement transfer means 22 to the base mass forceframe 4. This alternate method of design would be an alternateembodiment of the present invention.)

As the x axis moving table 12 and traveling support arm 14 of the lineardrive unit move in the x axis, the reactionary force experienced in thex axis stationary drive track 16 of the linear drive unit is transmittedthrough the x axis reactionary force movement transfer means 22 to thebase mass force frame 4 which is in turn transferred to the ground. Itis known that in other embodiments the x axis reactionary force movementtransfer means 22 may be of a single rigid arm and may be affixeddifferently to the stationary drive.

The y axis moving trolley assembly has a y axis moving carriage 24coupled to the y axis travelling arm 26 of the y axis linear drive unit.The y axis linear drive unit drives the y axis moving carriage 24 alonga y axis stationary (generally magnetic) drive track 28 based on asignal generated by the master control computer. This y axis travelingarm 26 is coupled to the y axis stationary drive track 28 for the y axislinear drive unit and is adapted for linear motion in the y axis by alow friction bearing means 30. Additional low friction y axis bearings30 act as a support between the back face of the y axis moving trolley24 and the front face of the metrology frame support base's y axissupport block 32. The y axis support block is an extension of themetrology frame support base 20. (Although shown as a U shaped blockprojecting normally from the section of the metrology frame support base20 that the traveling table 12 is supported on, it is known that anyconfiguration that is capable of supporting the y axis moving trolley 24could be substituted provided that it was isolated from the base massforce frame 4.)

The y axis stationary drive track 28 is decoupled from the metrologyframe support base's y axis support block 32 (and the rest of themetrology frame support base 20) by virtue of its direct coupling to thebase mass force frame 4 by the y axis reactionary force movementtransfer means 34. This is a rigid stanchion made of pair of rigid armswith a planar member extending between them. It can be made of a steel,a metal, a polymer or composite construction thereof and it is connectedto and supports the y axis stationary drive track 36. As the y axismoving carriage 24 and traveling arm 26 of the y axis linear drive unitmove in the y axis, the reactionary force experienced in the y axisstationary drive track 28 of the y axis linear drive unit is transmittedthrough the y axis reactionary force movement transfer means 34 to thebase mass force frame 4 which is in turn transferred to the ground. Itis known that in other embodiments the y axis reactionary force movementtransfer means 34 may employed. (Although it is known that the y axisreactionary force movement transfer means 34 may have a differentphysical configuration, it will remain a connection between the y axisstationary drive track 28 and the base mass force frame 4 and mustisolate the y axis stationary drive 36 from the metrology frame forcebase 20. Since the base mass force frame 4 is directly coupled to theground, connecting the y axis reactionary force movement transfer means22 directly to the ground rather than to the base mass force frame 4 isdeemed the equivalent to connecting the y axis reactionary forcemovement transfer means 32 to the base mass force frame 4. Thisalternate method of design would be an alternate embodiment of thepresent invention.)

Looking at FIGS. 8-10 the general arrangement of the z axis balancedreactionary force drill unit 36 can best be seen. As stated earlier, forpurposes of clarity the spindle rotating drive components (the drilldrive equipment) and the zero impact pressure foot components thatsecure the PCB substrates prior to the drilling are not illustrated.Each of these are subjects of earlier patents, and are well known inthis field of art and do not impose vibrational movements that aremeaningful to the accuracy of the PCB substrate positioning.

The drill unit 36 is mounted and oriented on the y axis moving carriage24 such that its linear axis and z axis drill stroke reside at 90degrees to the horizontal plane of the x axis moving table 12 and thehorizontal plane in which the y axis moving carriage travels. The drillunit 36 has a base plate 38 to which is affixed an upper guide sleeve 40and a lower guide sleeve 42 each of which house low friction guidebushing assemblies such as 5-25 micron orificed or porous carbon airsleeves. The drill unit 36 has a spindle 44 that resides inside the lowfriction guide bushing assembly housed in the lower guide sleeve 42. Thelower guide sleeve also houses the spindle motor. The spindle 44 holds adrill bit and is rotated at a high speed. The spindle 44 is driven orplunged downward in the z axis by a z axis spindle drive unit thatapplies an electric pulse that is provided to the voice coil 46 which isof a cup shaped design that fits up into a mating recess in the bottomof the voice coil magnet assembly 48. The voice coil magnet assembly 48is made of a voice coil magnet that is coupled to a reaction mass and ispartially housed within a low friction guide bushing assembly housedwithin the upper guide sleeve 40. There is a slender linear memberflexure 50 connecting the spindle 44 to the voice coil 46. This flexure50 deflects slightly to keep any angular distortion or deviance from thez axis travel of the spindle 44 minimized.

This conjoined voice coil magnet and reaction mass (voice coil magnetassembly) 48 has a mass several times greater than that of the voicecoil 46, flexure 50 and spindle 44 combined. In this manner, when theelectric pulse is sent to the voice coil 46 which resides partiallywithin the recess in the bottom of the voice coil magnet, the magneticfield generated in the voice coil 46 pushes against the magnetic fieldof the voice coil magnet and reaction mass 48, and because the mass ofthe voice coil 46, flexure 50 and spindle 44 combination is much lesserthan the mass of the voice coil magnet and reaction mass 48, thecombination of the voice coil 46, flexure 50 and spindle 44 are drivendownwards in the z axis. Simultaneously, the magnet and reaction mass 48are driven upwards in the z axis. The ratio of the length of the upwardsstroke of the voice coil magnet and reaction mass 48 to the length ofthe downwards stroke of the voice coil 46, flexure 50 and spindle 44 isproportional to their masses. If the mass of the voice coil magnet andreaction mass 48 is 10 times that of the voice coil 46, flexure 50 andspindle 44 combined, then for every one inch of spindle motion in thenegative z axis there will be a reactionary 0.1 inch movement of themagnet and reaction mass 48 in the positive z axis and vice versa. Sincethe reactionary force movement created when the spindle 44 plunges itsbit downward into the PCB substrate is dealt with by the opposing(balancing) movement of the magnet and reaction mass 48 upwards, thereis no unresolved forces or movement passed onto the drill unit 36 andthe metrology frame base 20. Thus, there are no unresolved reactionaryforces to disturb either the position feed back sensors or the drillinggeometry of the spindle 44.

Additionally, to aid in the minimizing of the reactionary forces, and toensure that the spindle and magnet always return or “settle” to the sameposition, a multi axis pivotable phase linkage 52 is connected betweenthe voice coil 46 and the voice coil magnet assembly 48. This phaselinkage is made of a series of sequentially connected linear members. InFIG. 9 the first member 56 (which is a linear arm) has a distal pivotalconnection 53 to the voice coil 46 and a proximate pivotal connection toa first end of an intermediate connection member 55. A stationary pivot54 is affixed to the bottom of the upper guide sleeve 40 and is alignedon the linear axis of the spindle 44. The first member 56 passeshorizontally through the pivot 54 such that the ratio of the distancefrom the pivot 54 to the distal pivotal connection 53 compared to thedistance from the pivot 54 to the proximate pivotal connection 56, isthe same ratio as that of the mass of the voice coil magnet and reactionmass 48 to that of the mass of the voice coil 46, flexure 50 and spindle44 combined. The second end of the intermediate connection member 55 isconnected to the last connection member 57 which is affixed to the voicecoil 46.

It is to be noted that the voice coil 46 and said voice coil magnetcoupled to said reaction mass 48 each simultaneously move in oppositedirections along the z axis. Since the mass of said voice coil 46,spindle 44 and said flexure 50 is less than a mass of said voice coilmagnet coupled to said reaction mass 48, the amount of their linearmovements are in proportion to their masses. For example, if thecombined mass of the voice coil 46, spindle 44 and said flexure 50 is100 grams and the combined mass of said voice coil magnet coupled tosaid reaction mass 48 is 1000 grams, then the voice coil 46, spindle 44and said flexure 50 will move 10 times further and in the opposite zaxis direction than the voice coil magnet coupled to said reaction mass48 will move.

The decoupled force frame/metrology frame design in conjunction with thebalanced reactionary force drill unit attempt to bring all of the netreactionary forces derived form the positioning and drilling functionsof the apparatus to zero within the metrology frame so as to allow muchmore efficient operation of the feedback sensors. This in turn increasesthe throughput of the device by allowing shorter sensor settle times,higher drill cycle times, more accurate drilling geometry, less brokenbits and a longer bit life.

The above description will enable any person skilled in the art to makeand use this invention. It also sets forth the best modes for carryingout this invention. There are numerous variations and modificationsthereof that will also remain readily apparent to others skilled in theart, now that the general principles of the present invention have beendisclosed. As such, those skilled in the art will appreciate that theconception, upon which this disclosure is based, may readily be utilizedas a basis for the designing of other structures, methods and systemsfor carrying out the several purposes of the present invention. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the present invention.

We claim:
 1. A PCB substrate drilling apparatus comprising: a base massforce frame; a meterology frame support base; at least one isolationdampener; an x axis linear drive unit having an x axis stationary drivetrack and a driveable, x axis traveling arm; a y axis linear drive unithaving a y axis stationary drive track and a driveable y axis travelingarm, a positionable x axis moving table assembly coupled to said x axistraveling arm and wherein said moving table assembly is moveablysupported on said meterology frame support base; a positionable y axismoving carriage coupled to said y axis traveling arm wherein said y axismoving carriage is moveably supported on an extension of said meterologyframe support base; at least one z axis drill unit coupled to said yaxis moving carriage; an x axis reactionary force movement transfermeans that supports said x axis stationary drive track and is anextension of said base mass force frame; and a y axis reactionary forcemovement transfer means that supports said y axis stationary drive trackand is an extension of said base mass force frame; wherein saidmeterology frame support base and said base mass force frame areseparated by at least one of said isolation dampeners.
 2. The PCBsubstrate drilling apparatus of claim 1 further comprising at least onevibration isolation dampener positioned between said base mass forceframe and said metrology frame support base.
 3. The PCB substratedrilling apparatus of claim 1 wherein said z axis drill unit is abalanced reactionary force drill unit that comprises: drill unit baseplate connected to said moving carriage; a z axis moveable drill spindlerotationally housed in a first guide bushing assembly that is mounted ina lower guide sleeve affixed to said drill unit base plate; a z axismoveable spindle drive unit moveably housed in a second guide bushingassembly that is mounted in an upper guide sleeve affixed to said drillunit base plate; a flexure connector affixed between said spindle andsaid z axis spindle drive unit.
 4. The PCB substrate drilling apparatusof claim 3 wherein said z axis spindle drive unit comprises a voice coilmoveably housed within a portion of a moveable voice coil magnet coupledto a reaction mass.
 5. The PCB substrate drilling apparatus of claim 4wherein said spindle and said flexure combined have a first mass, andsaid voice coil magnet and coupled reaction mass combined have a secondmass, and wherein said first mass is less than said second mass.
 6. ThePCB substrate drilling apparatus of claim 5 wherein said z axis drillunit has a series of sequentially joined connection members forming apivotable phase linkage, wherein a first connection member is pivotallyaffixed to said voice coil magnet and a last connection member isaffixed to said voice coil, and wherein said first connection memberalso is affixed to the bottom of said upper guide sleeve by a pivotsupport that extends from said upper guide sleeve and is aligned along alinear axis of the spindle, wherein said first connection member passeshorizontally through said pivot and the ratio of the distance from saidpivot to a distal end of said first connection member compared to thedistance from said pivot to a proximate end of said first connectionmember approximates the ratio of a combined mass of the magnet and thereaction mass to a combined mass of the voice coil, the flexure and thespindle.
 7. The PCB substrate drilling apparatus of claim 2 wherein saidat least one vibration isolation dampener has an upper contact point onsaid metrology frame support base and a lower contact point on said basemass force frame and wherein said upper contact point lies along acenter of gravity plane for said metrology frame support base.
 8. ThePCB substrate drilling apparatus of claim 6 further comprising anintermediate connection member connected between said first connectionmember and said last connection member.
 9. A PCB substrate drillingapparatus comprising: a supporting base; an x axis linear drive unitresiding on said supporting base and having an x axis stationary drivetrack and an x axis traveling arm; a y axis linear drive unit residingon said supporting base and having a y axis stationary drive track and ay axis traveling arm; a positionable x axis moving table assemblycoupled to said x axis traveling arm; a positionable y axis movingcarriage coupled to said y axis traveling arm; a z axis balancedreactionary force drill unit coupled to said y axis moving carriage,wherein said z axis reactionary force drill unit comprises a drill unitbase plate connected to said moving carriage, a z axis moveable drillspindle rotationally housed in a first guide bushing assembly that ismounted in a lower guide sleeve affixed to said drill unit base plate; az axis spindle drive unit comprised of a voice coil and a voice coilmagnet coupled to a reaction mass wherein said voice coil is partiallyhoused within a recess in said voice coil magnet, and wherein said zaxis spindle drive unit is moveably housed in a second guide bushingassembly that is mounted in an upper guide sleeve affixed to said drillunit base plate, wherein said voice coil and said voice magnet coupledto said reaction mass are each simultaneously moveable in oppositedirections along the z axis; wherein a mass of said voice coil, saidspindle and a flexure is less than a mass of said voice coil magnetcoupled to said reaction mass; and said flexure connector affixedbetween said spindle and said z axis spindle drive unit; wherein said zaxis drill unit has a series of sequentially joined connection membersforming a pivotable phase linkage, wherein a first connection member ispivotally affixed to said voice coil magnet and a last connection memberis affixed to said voice coil, and wherein said first connection memberalso is affixed to the bottom of said upper guide sleeve by a pivotsupport that extends from said upper guide sleeve and is aligned along alinear axis of the spindle, wherein said first connection member passeshorizontally through said pivot and the ratio of the distance from saidpivot to a distal end of said first connection member compared to thedistance from said pivot to a proximate end of said first connectionmember approximates the ratio of a combined mass of the magnet and thereaction mass to a combined mass of the voice coil, the flexure and thespindle.
 10. The PCB substrate drilling apparatus of claim 9 whereinsaid supporting base is comprised of: a metrology frame support base; abase mass force frame; and at least one compressive isolation dampener;wherein said meterology frame support base resides atop of said basemass force frame but separated by said base mass force frame by at leastone of said compressive isolation dampeners.
 11. The PCB substratedrilling apparatus of claim 9 wherein said x axis stationary drive trackand said y axis stationary drive track are affixed to said base massforce frame, and said x axis travelling arm is connected to said movingtable assembly that is moveably supported on said meterology framesupport base, and said y axis travelling arm is connected to a saidmoving carriage that is moveably supported on said meterology framesupport base.
 12. The PCB substrate drilling apparatus of claim 10wherein said x axis stationary drive track is affixed to said base massforce by an x axis reactionary force movement transfer means, and said yaxis stationary drive track are affixed to said base mass force frame bya y axis reactionary force movement transfer means.
 13. The PCBsubstrate drilling apparatus of claim 11 wherein said vibrationisolation dampener has an upper contact point on said metrology framesupport base and a lower contact point on said base mass force frame andwherein said upper contact point lies along a center of gravity planefor said metrology frame support base.
 14. The PCB substrate drillingapparatus of claim 13 wherein said metrology frame support base has astopped vertical orifice defined therein having an upper face thatresides parallel to said center of gravity plane and contacts said atleast one vibration isolation dampener's upper contact point.